JP3126902B2 - Cellulose acetate fiber having special cross section and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cellulose acetate fiber having a special cross section and a method for producing the same. More specifically, by adding polyethylene glycol to the acetate spinning stock solution and dry spinning at a temperature lower than the normal spinning stock temperature, it has an unprecedented special cross-sectional shape, and has excellent gloss and texture. The present invention relates to a cellulose acetate fiber having the same and a method for producing the same.

[0002]

2. Description of the Related Art Cellulose acetate fibers (hereinafter, also referred to as "acetate") have excellent coloring properties and a dry feeling, and exhibit excellent properties as materials for fashion and the like. However, in recent years, consumer needs for textiles have been upgraded and diversified, and further improvements and improvements have been desired.

[0003] Regarding the cross-sectional shape of the yarn, in the case of acetate fibers, a stock solution of acetate flakes, which is a raw material, in a solvent such as acetone or methylene chloride is discharged from a spinneret to evaporate the solvent in a spinning cylinder. Therefore, even if the spinning solution is discharged from a spinneret having a circular spinning hole, the cross section of the spinning solution at the stage of winding as a yarn has a large number of irregularities. This is because when the yarn is dried in the spinning cylinder, the outer part of the yarn firstly dries to form a skin, and the solvent inside is further evaporated and removed, so that it is formed earlier by that much. It is believed that the skin partly enters the inside of the thread and forms irregularities.

Conventionally, as a means for changing the cross-sectional shape of the acetate fiber, a method of devising a spinneret has been adopted.
For example, Japanese Patent Publication No. 37-7917 discloses an attempt to discharge a spinning solution from a spinneret having a triangular or square spinning hole. Also, Japanese Patent Application Laid-Open No. Sho 60-13401
In Japanese Patent Publication No. 2 (1993), Y-shaped acetate fibers are obtained by forming a plurality of spinning holes having a specific cross-sectional shape at specific intervals. Further, in JP-A-3-59105, the inner tube is discharged from the end face of the outer die, and the outer diameter of the discharge portion is determined.
Attempts have been made to obtain acetate fibers having a hollow cross section by using a double-tube type spinneret whose length is adjusted to a specific range. However, in these prior arts, none of them can change the drying state of the solvent, and it is difficult to form a thread having the same number of projections and depressions, and a thread whose cross-sectional shape is significantly different from the desired shape is mixed. I was

[0005]

DISCLOSURE OF THE INVENTION The present invention reduces the unevenness of the cross-sectional shape of an acetate fiber and has a unique gloss and texture having a cross-sectional shape which could not be obtained by a method for improving a spinneret. It is an object of the present invention to provide an acetate fiber having:

[0006]

SUMMARY OF THE INVENTION The present invention has a substantially eye-shaped cross-sectional shape in which two convex portions are connected via a concave portion, and the concave portion is formed from the side of the adjacent convex portion that protrudes more. A cellulose acetate fiber having a special cross section, characterized in that at least 60% of single yarns having a depth of a concave portion corresponding to a distance to the bottom of 5 μm or less are present.

[0007] The present invention also provides an acetate flake,
When a spinning solution prepared by mixing 5 to 40% by weight of polyethylene glycol with respect to acetate flakes and a solvent dissolvable in acetate flakes and polyethylene glycol is discharged from the spinneret using a spinneret having a circular spinning hole. The spinning dough temperature of 55 to 55
A method for producing a cellulose acetate fiber having the above-mentioned special cross section, wherein the cellulose acetate fiber is spun at 62 ° C.

The cellulose acetate to be used in the present invention is an acetate ester in which an average of 1 to 3 hydroxyl groups out of 3 hydroxyl groups present in a repeating unit of cellulose is an acetate ester, and particularly an average of 1.9. Those in which 2.8 are esterified (acetylation degree 47-60%) are preferred.

As shown in FIG. 1, the acetate fiber (single yarn) 10 of the present invention has a substantially eye-shaped cross-sectional shape in which two convex portions 11 and 12 are connected via a concave portion 13. In addition, the depth t of the concave portion corresponding to the distance from the more protruding side 11a, 12a of the adjacent convex portions 11, 12 to the bottom 13a of the concave portion is 5 μm or less, preferably 3 μm.
m or less. If the depth exceeds 5 μm, the central portion of the cross section becomes thin and breaks, resulting in a cross-sectional shape greatly deviating from the eyebrow shape.

[0010] The acetate fiber (multifilament) of the present invention comprises 60% of a single yarn having the above-mentioned cross-sectional shape.
As described above, the content is preferably 80% or more, and if it is less than 60%, the gloss and hand of the fabric are not improved.

In general, acetate fibers are obtained by dissolving acetate flakes in a solvent such as acetone or methylene chloride to prepare a spinning solution, discharging the solution from a spinneret having a circular spinning hole, and performing dry spinning. In this dry spinning, the solvent evaporates and hardens at the same time as the spinning solution is discharged from the spinneret. At this time, the outer side hardens first, and the skin is formed, and the inner solvent is removed. When it exits, it partially enters the inside, creating irregularities. When a normal spinning solution is used, this degree is large, and the depth of the concave portion is 6 to 10 μm.

In order to obtain the acetate fiber of the present invention, the addition of polyethylene glycol to the spinning dope delays the formation of the skin and hardens after the solvent inside is removed, so that the skin enters the inside of the yarn. Since the degree of the change is reduced and the change in the shape is suppressed, the unevenness is reduced, and a substantially eye-shaped cross-sectional shape is maintained.

The molecular weight of the polyethylene glycol contained in the acetate is not particularly limited, but is preferably 25,000 or less, more preferably 20,000 or less, in view of compatibility with the spinning solution. If it exceeds 25,000, the compatibility with the stock solution for spinning becomes poor and the spinning condition becomes poor.

The amount of polyethylene glycol to be added is 5 to 40% by weight, preferably 20 to 30% by weight, based on acetate. When the amount is less than 5% by weight, the special cross-sectional shape of the present invention cannot be obtained.

Further, in the present invention, when dry spinning is performed using an acetate spinning solution containing polyethylene glycol, the temperature of the spinning solution discharged from the spinneret is 55 to 62 ° C., preferably 58 to 60 ° C. Need to keep. The spinning dope temperature when dry spinning the acetate fiber is usually higher than 62 ° C. and 70 ° C. or lower. In the present invention, by setting the temperature in the above range lower than the normal spinning solution temperature, an acetate fiber having a special cross-sectional shape intended for the present invention can be obtained. When the temperature of the spinning dope is lower than 55 ° C., the solvent in the spinning dope is not sufficiently dried, which causes breakage of the yarn. On the other hand, if it is higher than 62 ° C,
The drying state of the solvent changes, and the number of concaves and convexes per single yarn decreases, but a large number of concaves whose depth of the concaves exceeds 5 μm appears.

The polyethylene glycol can be added to the undiluted solution of acetate spinning, for example, by dissolving cellulose acetate in a solvent such as acetone or methylene chloride, that is, by adding the undiluted solution of acetate spinning, or by applying heat to polyethylene glycol. And spinning the mixture into a spinning machine while mixing it with an undiluted solution for acetate spinning at a ratio to obtain a desired content, and performing dry spinning. At this time, dry spinning conditions are a draft ratio of 1.1 to 1.4 and a winding speed of about 200 to 900 m / min.

The added polyethylene glycol is eluted during refining after fabric formation, but the cross-sectional shape of the fiber is not changed by this.

[0018]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. In addition, various evaluations in the examples were measured as follows.

Section ratio: As shown in FIG.
The percentage of the number of single yarns in the acetate fiber (multifilament) having a depth t of the concave portion of 5 μm or less is indicated by%. Using the obtained acetate fiber (multifilament), a tubular knit was prepared, and the luster after removing the oil agent and polyethylene glycol by refining was visually evaluated. In addition, the comparative example 8 was judged as standard (good), and what was better than this was extremely good. The tubular knitted fabric treated in the same manner as in the evaluation of hand gloss was evaluated by touch. In addition, Comparative Example 8 was determined to be standard (good), and a sample having good bulkiness by dry touch was judged to be extremely good.

Examples 1 to 8 and Comparative Examples 1 to 6 A total of 31 parts by weight of cellulose acetate flakes having an average acetylation degree of 54.7% and polyethylene glycol (PEG) in the proportions shown in Table 1, 68 parts by weight of acetone, One part by weight of water was mixed and defoamed to prepare a uniform spinning solution. This spinning dope was dried in a dry spinning apparatus under the conditions shown in Table 1.
Using a spinneret having a circular spinning hole having a hole diameter of 50 μm and 33 holes, a draft ratio of 1.2 and a winding speed of 700 were adjusted while adjusting the temperature of the spinning stock solution at the time of discharging to a desired temperature.
Dry spinning was performed at m / min to obtain an acetate fiber of 120 denier / 33 filaments. Table 1 shows the results. In addition,
FIGS. 2 and 3 are micrographs (400 × magnification) of the cross-sectional shapes of the acetate fibers obtained in Example 7 and Comparative Example 4, respectively.
As shown in FIG.

Comparative Examples 7 and 8 24 parts by weight of cellulose acetate flake having an average acetylation degree of 54.7%, 75 parts by weight of acetone and 1 part by weight of water were mixed and defoamed to prepare a uniform spinning solution. The spinning dope was subjected to dry spinning under the conditions shown in Table 1 to obtain a pore diameter of 50 μm.
m, using a spinneret having a circular spinning hole having 33 holes, while performing the dry spinning under the same dry spinning conditions as in Example 1 while adjusting the spinning stock solution temperature at the time of discharge to a desired temperature, 12
An acetate fiber of 0 denier / 33 filaments was obtained. Table 1 shows the results.

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to obtain an acetate fiber having a uniform and special cross section, which has not been obtained before, and to provide an acetate fabric having excellent gloss and feeling.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic view of a cross section of an acetate fiber having a special cross section according to the present invention.

FIG. 2 is a micrograph (400 × magnification) of a cross section of the acetate fiber obtained in Example 7.

FIG. 3 is a micrograph (400 × magnification) of a cross section of the acetate fiber obtained in Comparative Example 4.

[Explanation of symbols]

 Reference Signs List 10 acetate fiber (single yarn) 11, 12 convex portion 13 concave portion t depth of concave portion

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D01F 2/28-2/30 D01D 5/04 D01D 5/253 D01D 1/09

Claims (3)

(57) [Claims] 1. It has a substantially eye-shaped cross-sectional shape in which two convex portions are connected via a concave portion, and corresponds to the distance from the more protruding side of the adjacent convex portions to the bottom of the concave portion. Cellulose acetate fiber having a special cross-section, wherein 60% or more of a single yarn having a concave portion having a depth of 5 µm or less is present. 2. The cellulose acetate fiber having a special cross section according to claim 1, wherein the fiber formed during dry spinning contains 5 to 40% by weight of polyethylene glycol. 3. A spinning method having a circular spinning hole, comprising cellulose acetate flakes and a spinning dope obtained by mixing 5 to 40% by weight of polyethylene glycol with respect to the cellulose acetate flakes and a solvent dissolvable in the cellulose acetate flakes and polyethylene glycol. 2. The method for producing cellulose acetate fiber having a special cross-section according to claim 1, wherein the spinning solution is spun at a temperature of from 55 to 62 [deg.] C. using a spinneret.